Gradualism is rarely observed in the fossil record because:a
too may species are extinct.
b. the fossil record is incomplete.
c. not enough species have evolved.
d. very few instances of speciation have been observed.
e. more scientists believe in the model of punctuated equilibrium.
b
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Which of the following mutations is most likely to cause a phenotypic change?
A) a duplication of all or most introns B) a large inversion whose ends are each in the same region between genes C) a nucleotide substitution in an exon coding for a transmembrane domain D) a single nucleotide deletion in an exon coding for an active site E) a frameshift mutation one codon away from the end of the nontemplate strand
Answer the question using the accompanying graph. Which portion of the graph shows the activation energy in the
presence of enzyme?
a. A b. B c. C d. W + X e. Y + Z
IN HUMANS FREE EARLOBES ARE DOMINANT TO ATTACHED EARLOBES. IF AN INDIVIDUAL IS HETEROZYGOUS FOR THE EARLOBES TRAIT MATED WITH AN INDIVIDUAL WITH ATTACHED EAR LOBES WHATS THE PROBABILITY OF A CHILD WITH ATTACHED EARLOBES?
A. 0% B. 25% C. 50% D. 100%
While characterizing the activities of several neurons, you find a neuron with the following properties:
(1) When stimulated, the neuron fails to release neurotransmitters into the synaptic cleft. (2) Microinjection of calcium ions calcium ions has no effect on the neuron. (In other neurons such microinjection stimulates the t-SNARE and v-SNARE complex interaction that promotes neurotransmitter secretion.) The abnormality in this neuron is most likely associated with the function of A) the vesicle membranes. B) acetylcholinesterase. C) synaptotagmin. D) GABA receptors. E) gap junctions.